This invention relates to a process and apparatus for dispensing a volatile air freshener into circulating room air, and more particularly to a process and apparatus for dispensing volatized air freshener compound into the air as the air is being filtered by an air filtering apparatus.
The invention is particularly adapted for use in connection with an air filtering apparatus of the type described in my U.S. Pat. No. 3,936,284 wherein air is drawn into a filter cabinet through a prefilter and is forced outwardly through a high efficiency HEPA type filter by means of the fan disposed in the space between these filters. Such an apparatus removes from the air such large particulates as street and house dust as well as sub-micronic size particulates such as tobacco smoke and typical airborne bacteria and viruses. The filter serves to remove by adsorption a wide variety of odors from the air being filtered. However, many odors which are caused by gases and particulates smaller than about 0.3 micron in size, may not be effectively removed by the filter apparatus. In order to treat the air containing odors originating from such sources, liquid malodor modifiers or air freshener chemicals have been employed. These are generally of two types: (a) those which mask odors, and (b) those which remove odors. Such air freshener chemicals are frequently used in households and are available in various familiar forms, including solids and liquids, with the liquid type being dispensed either by means of spraying or by means of a capillary wick which increases the surface area of contact between the liquid air freshener and the room air.
Heretofore, liquid air freshener chemicals have been added to the filtered air in an air filtering apparatus of the type illustrated in my U.S. Pat. No. 2,936,284. This has been done by positioning an open trough downstream from the high efficiency filter element, i.e., between that element and the exterior grid of the filter apparatus cabinet. The liquid air freshener was poured into this trough and was permitted to constantly evaporate into the filtered air as it flowed from the air filtering apparatus. Unfortunately, that arrangement provided no control over the amount of the air freshener that was being dispensed into the air, and as a result, either the liquid air freshener rapidly evaporated and the unit was operated without any air freshener, or an undesirable overabundance of the air freshener was dispensed into the air.
Another method previously used is the placement of an air freshener liquid or gel within the cabinet of the air filtering apparatus at the intake end. The air freshener was continuously volatilized into the air until the supply was exhausted or removed. Removal or closure of the container for the air freshener required turning the unit off and removing a section of the air filtering apparatus housing or enclosure in order to gain access to the air freshener.
These prior methods in reality provided no control over the dispensing of air freshener into the air.
One object of this invention is to provide a control over the dispensing of the air freshener into the air as it is flowing through the air filtering apparatus. The control provided by this invention (1) permits the air freshener dispensing to be adjusted from the exterior of the cabinet without requiring dismantling of any part of the cabinet and (2) provides an accurate means of varying the amount of air freshener media released into the room air. The control prevents the dispensing of air freshener when unnecessary and it permits the air freshener to be dispensed selectively in predetermined measured amounts depending upon the user's requirements. Thus, the air freshener liquid can be used much more economically and only in the quantities necessary to overcome the odors in the room.
It has been found that when the air freshener is dispensed by volatilization into the air upstream of the high efficiency or HEPA type filter, it serves not only to remove the odors from the air but it also tends to remove the odors from the upstream side of the filter. Over a period of several months the upstream side of the HEPA type filter traps particulates which are malodorous and to some extent the filter adsorbs malodorous gases. In previous application of air freshener chemicals to the air downstream of the HEPA type filter there was no effect upon the HEPA type filter itself. However, with the present invention the HEPA type filter may in effect be "cleansed" of these odors because the air carrying the air freshener will impinge upon the trapped particles and adsorb gases on the upstream side of the HEPA type filter.